/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

\*---------------------------------------------------------------------------*/

#include "triSurface.H"
#include "IFstream.H"
#include "IStringStream.H"


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

bool Foam::triSurface::readGTS(const fileName& GTSfileName)
{
    IFstream GTSfile(GTSfileName);

    if (!GTSfile.good())
    {
        FatalErrorInFunction
            << "Cannot read file " << GTSfileName
            << exit(FatalError);
    }

    // Read header
    label nPoints, nEdges, nElems;

    string line = getLineNoComment(GTSfile);
    {
        IStringStream lineStream(line);
        lineStream >> nPoints >> nEdges >> nElems;
    }

    // Read points
    pointField& points_ = const_cast<pointField&>(points());
    points_.setSize(nPoints);

    forAll(points_, pointi)
    {
        scalar x, y, z;
        line = getLineNoComment(GTSfile);
        {
            IStringStream lineStream(line);
            lineStream >> x >> y >> z;
        }
        points_[pointi] = point(x, y, z);
    }

    // Read edges (Foam indexing)
    edgeList edges(nEdges);
    forAll(edges, edgei)
    {
        label start, end;
        line = getLineNoComment(GTSfile);
        {
            IStringStream lineStream(line);
            lineStream >> start >> end;
        }
        edges[edgei] = edge(start - 1, end - 1);
    }

    // Read triangles. Convert references to edges into pointlabels
    setSize(nElems);
    forAll(*this, trianglei)
    {
        label e0Label, e1Label, e2Label;
        label region = 0;

        line = getLineNoComment(GTSfile);
        {
            IStringStream lineStream(line);
            lineStream >> e0Label >> e1Label >> e2Label;

            // Optional region number: read first, then check state on stream
            if (lineStream)
            {
                label num;
                lineStream >> num;
                if (!lineStream.bad())
                {
                    region = num;
                }
            }
        }

        // Determine ordering of edges e0, e1
        //  common:common vertex, shared by e0 and e1
        //  e0Far:vertex on e0 which is not common
        //  e1Far: ,,       e1  ,,
        const edge& e0 = edges[e0Label - 1];
        const edge& e1 = edges[e1Label - 1];
        const edge& e2 = edges[e2Label - 1];

        label common01 = e0.commonVertex(e1);
        if (common01 == -1)
        {
            FatalErrorInFunction
                << "Edges 0 and 1 of triangle " << trianglei
                << " do not share a point.\n"
                << "    edge0:" << e0 << endl
                << "    edge1:" << e1
                << exit(FatalError);
        }

        label e0Far = e0.otherVertex(common01);
        label e1Far = e1.otherVertex(common01);

        label common12 = e1.commonVertex(e2);
        if (common12 == -1)
        {
            FatalErrorInFunction
                << "Edges 1 and 2 of triangle " << trianglei
                << " do not share a point.\n"
                << "    edge1:" << e1 << endl
                << "    edge2:" << e2
                << exit(FatalError);
        }
        label e2Far = e2.otherVertex(common12);

        // Does edge2 sit between edge1 and 0?
        if ((common12 != e1Far) || (e2Far != e0Far))
        {
            FatalErrorInFunction
                << "Edges of triangle " << trianglei
                << " reference more than three points.\n"
                << "    edge0:" << e0 << endl
                << "    edge1:" << e1 << endl
                << "    edge2:" << e2 << endl
                << exit(FatalError);
        }

        operator[](trianglei) = labelledTri(e0Far, common01, e1Far, region);
    }

    // Construct patch names
    setDefaultPatches();

    return true;
}


// ************************************************************************* //
